Cleanup usage of scoped_ptr<> in remoting for C++11

remoting/codec/audio_encoder_opus.cc

Index: remoting/codec/audio_encoder_opus.cc
diff --git a/remoting/codec/audio_encoder_opus.cc b/remoting/codec/audio_encoder_opus.cc
index 53bfe0b0c0893acd58b384e586224f63b58effe6..b2a9b5eafe431463908e1a1bf85215e36a5dce2a 100644
--- a/remoting/codec/audio_encoder_opus.cc
+++ b/remoting/codec/audio_encoder_opus.cc
@@ -142,7 +142,7 @@ scoped_ptr<AudioPacket> AudioEncoderOpus::Encode(
 
   if (!ResetForPacket(packet.get())) {
     LOG(ERROR) << "Encoder initialization failed";
-    return scoped_ptr<AudioPacket>();
+    return nullptr;
   }
 
   int samples_in_packet = packet->data(0).size() / kBytesPerSample / channels_;
@@ -200,7 +200,7 @@ scoped_ptr<AudioPacket> AudioEncoderOpus::Encode(
                              buffer, data->length());
     if (result < 0) {
       LOG(ERROR) << "opus_encode() failed with error code: " << result;
-      return scoped_ptr<AudioPacket>();
+      return nullptr;
     }
 
     DCHECK_LE(result, static_cast<int>(data->length()));
@@ -230,7 +230,7 @@ scoped_ptr<AudioPacket> AudioEncoderOpus::Encode(
 
   // Return NULL if there's nothing in the packet.
   if (encoded_packet->data_size() == 0)
-    return scoped_ptr<AudioPacket>();
+    return nullptr;
 
   return encoded_packet.Pass();
 }